International Patent Publication No. WO 00/72801 discloses a series of 3-substituted nonanoic acid derivatives of use as ανβ3 receptor antagonists, including compounds of the formula (A):
wherein n is 2 or 3.
The synthetic methods given in that application work well on a small scale, but the process is linear and requires a chiral HPLC separation of enantiomers of a penultimate intermediate. The δ-keto-acid moiety within the compound of formula (A) contains the only stereogenic carbon. There is therefore a need for an enantioselective and more efficient synthetic route to the compound of formula (A).